pragma solidity ^0.4.24;

/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
  address private _owner;

  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );

  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  constructor() internal {
    _owner = msg.sender;
    emit OwnershipTransferred(address(0), _owner);
  }

  /**
   * @return the address of the owner.
   */
  function owner() public view returns (address) {
    return _owner;
  }

  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    require(isOwner());
    _;
  }

  /**
   * @return true if `msg.sender` is the owner of the contract.
   */
  function isOwner() public view returns (bool) {
    return msg.sender == _owner;
  }

  /**
   * @dev Allows the current owner to relinquish control of the contract.
   * @notice Renouncing to ownership will leave the contract without an owner.
   * It will not be possible to call the functions with the `onlyOwner`
   * modifier anymore.
   */
  function renounceOwnership() public onlyOwner {
    emit OwnershipTransferred(_owner, address(0));
    _owner = address(0);
  }

  /**
   * @dev Allows the current owner to transfer control of the contract to a newOwner.
   * @param newOwner The address to transfer ownership to.
   */
  function transferOwnership(address newOwner) public onlyOwner {
    _transferOwnership(newOwner);
  }

  /**
   * @dev Transfers control of the contract to a newOwner.
   * @param newOwner The address to transfer ownership to.
   */
  function _transferOwnership(address newOwner) internal {
    require(newOwner != address(0));
    emit OwnershipTransferred(_owner, newOwner);
    _owner = newOwner;
  }
}

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
interface IERC20 {
  function totalSupply() external view returns (uint256);

  function balanceOf(address who) external view returns (uint256);

  function allowance(address owner, address spender) external view returns (uint256);

  function transfer(address to, uint256 value) external returns (bool);

  function approve(address spender, uint256 value) external returns (bool);

  function transferFrom(address from, address to, uint256 value) external returns (bool);

  event Transfer(
    address indexed from,
    address indexed to,
    uint256 value
  );

  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}

/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, reverts on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
    // benefit is lost if 'b' is also tested.
    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint256 c = a * b;
    require(c / a == b);

    return c;
  }

  /**
  * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0);
    // Solidity only automatically asserts when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;
  }

  /**
  * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    uint256 c = a - b;

    return c;
  }

  /**
  * @dev Adds two numbers, reverts on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a);

    return c;
  }

  /**
  * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
  * reverts when dividing by zero.
  */
  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0);
    return a % b;
  }
}

/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
 * Originally based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract ERC20 is IERC20, Ownable {
  using SafeMath for uint256;

  mapping(address => uint256) private _balances;
  mapping(address => bool) private _frozen;

  mapping(address => mapping(address => uint256)) private _allowed;

  uint256 private _totalSupply = 100000000000000000000000000;

  constructor() public {
    _balances[address(this)] = _totalSupply;
    emit Transfer(address(0x0), address(this), _totalSupply);
  }

  /**
  * @param _address The address to be frozen/unfrozen.
  * @param _boolean The flag to set frozen if true and unfrozen if false.
  */
  function freeze(address _address, bool _boolean) external onlyOwner {
    _frozen[_address] = _boolean;
  }

  /**
   * @param owner The address to be checked.
   * @return A bool representing of the address state frozen if true and unfrozen if false.
   */
  function isFrozen(address owner) public view returns (bool) {
    return _frozen[owner];
  }

  /**
  * @dev Total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param owner The address to query the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address owner) public view returns (uint256) {
    return _balances[owner];
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param owner address The address which owns the funds.
   * @param spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(address owner, address spender) public view returns (uint256){
    return _allowed[owner][spender];
  }

  /**
  * @dev Transfer token for a specified address
  * @param to The address to transfer to.
  * @param value The amount to be transferred.
  */
  function transfer(address to, uint256 value) public returns (bool) {
    require(!isFrozen(msg.sender));
    _transfer(msg.sender, to, value);
    return true;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   * Beware that changing an allowance with this method brings the risk that someone may use both the old
   * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
   * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
   * @param spender The address which will spend the funds.
   * @param value The amount of tokens to be spent.
   */
  function approve(address spender, uint256 value) public returns (bool) {
    require(spender != address(0));

    _allowed[msg.sender][spender] = value;
    emit Approval(msg.sender, spender, value);
    return true;
  }

  /**
   * @dev Transfer tokens from one address to another
   * @param from address The address which you want to send tokens from
   * @param to address The address which you want to transfer to
   * @param value uint256 the amount of tokens to be transferred
   */
  function transferFrom(address from, address to, uint256 value) public returns (bool){
    require(value <= _allowed[from][msg.sender]);
    require(!isFrozen(from));

    _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
    _transfer(from, to, value);
    return true;
  }

  /**
   * @dev Increase the amount of tokens that an owner allowed to a spender.
   * approve should be called when allowed_[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param spender The address which will spend the funds.
   * @param addedValue The amount of tokens to increase the allowance by.
   */
  function increaseAllowance(address spender, uint256 addedValue) public returns (bool){
    require(spender != address(0));

    _allowed[msg.sender][spender] = _allowed[msg.sender][spender].add(addedValue);
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  /**
   * @dev Decrease the amount of tokens that an owner allowed to a spender.
   * approve should be called when allowed_[_spender] == 0. To decrement
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param spender The address which will spend the funds.
   * @param subtractedValue The amount of tokens to decrease the allowance by.
   */
  function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool){
    require(spender != address(0));

    _allowed[msg.sender][spender] = _allowed[msg.sender][spender].sub(subtractedValue);
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  /**
  * @dev Transfer token for a specified addresses
  * @param from The address to transfer from.
  * @param to The address to transfer to.
  * @param value The amount to be transferred.
  */
  function _transfer(address from, address to, uint256 value) internal {
    require(value <= _balances[from]);
    require(to != address(0));

    _balances[from] = _balances[from].sub(value);
    _balances[to] = _balances[to].add(value);
    emit Transfer(from, to, value);
  }

  /**
  * @param to The address to receive tokens.
  * @param value The number of tokens to receive.
  */
  function transferTokens(address to, uint256 value) external onlyOwner {
    require(value <= _balances[address(this)]);
    require(to != address(0));

    _balances[address(this)] = _balances[address(this)].sub(value);
    _balances[to] = _balances[to].add(value);
    emit Transfer(address(this), to, value);
  }

  /**
  * @param to The array of addresses to receive tokens.
  * @param value The array of numbers of tokens to receive.
  */
  function airdrop(address[] to, uint256[] value) external onlyOwner {
    require(to.length == value.length);
    for (uint i = 0; i < to.length; i++) {
      _transfer(address(this), to[i], value[i]);
    }
  }
}

contract UbaiCoin is ERC20 {
  string constant public name = "UBAI COIN";
  string constant public symbol = "UBAI";
  uint256 constant public decimals = 18;
}